I have a fairly new heat pump; it’s a 2010 Goodman gsz13 13 seer with the air handler in the attic. Is there anyway to add a gas furnace to the system without changing the whole system? (There is a gas hook up to the house, just not hooked up.) We have had some what of a cold winter, here in va. The heat pump doesn’t make that great of heat and we have some what high electric bills.